Introduction

 

In two large studies, one of them carried out in Colorado and Utah and the other in New York, it was observed an adverse event occurrence of 2.9 % and 3.7 % of admissions.

These events derived in deaths in 6.6 % of the Colorado and Utah hospitals and in 13.6 % of the New York ones. In both studies half of the events were secondary to medical errors that could have been prevented.

If these figures were extrapolated to the 33.6 million U. S. hospital admissions in 1997, one could infer that between 44,000 (Colorado and Utah study) and 98,000 (New York study) people would have died that year as a result of medical errors.

At the same time 43,458 deaths were registered due to car crashes, 42,297 due to breast cancer and 16,516 due to AIDS.1 These shocking figures lead us to rethink about how could we avoid such errors by its prevention.

We could define “error” (from Latin: errorem) as a wrong or mistaken action.2

In those procedures that require practical training for its performance, one of the causes of these foreseeable errors are tactics and/or techniques wrongly applied.

Since long ago the physicians were trained by means of experimental surgery in animals in order to learn suture techniques or tissue anastomoses, before doing it in humans. One bowel, arterial or venous anastomosis has first to be learnt in non-stressing conditions so that it can be repeated and corrected without undesired consequences for people.3

Nonetheless, this learning strategy could have ethic implications on one side and impossibility of reproduction of all possible human situations on the other.

In the last 15 years we have witnessed an impressive development of informatics, expanding uninterruptedly to all human areas.

Incorporation of simulators for medical training is today a reality that is enhancing year after year.

About learning

 

We could define “learning” as a relatively permanent behavioral change that occurs as the result of practice.4

It can be classified in three domains, being them:

 

1. Cognitive or intellectual: comprises intellectual skills and capabilities, including memory and knowledge evocation (verbal information, concepts, principles or generalizations, problem resolution, critical thinking).

2. Psychomotor: manual abilities or any act requiring neuromuscular coordination (skills).

3. Affective: interests, attitudes and values (attitudes).

 

Even though all of we act involving the three domains in all our actions, circumstantial predominance of any of them can be useful with pedagogical purposes.

An individual learns: a) spoken information, b) concepts, c) principles, d) problem resolution, e) critical thinking, f) psychomotor skills and g) attitudes.

While achieving psychomotor skills there exist three moments: 1) acquisition, 2) fixation and 3) perfectioning, having practice and demonstrations a key role.

Table 1 summarizes the Fitts-Posner’s three-stage theory of acquisition of motor abilities related with skills. 5

For the performance of complex handwork such as that required for surgical interventions it’s necessary not only to understand the task to handle but also its integration and automation. Is in this scenario where simulators emerge with a relevant role.

 

Simulators

 

For the teaching/learning of these skills 5 simulator types are available, being them (Table 2)5: a) bench models, b) live animals, c) cadavers, d) human performance simulators, e) virtual reality simulators. Each of them has its advantages and disadvantages.

The bench models in endovascular areas have generally been made of transparent glass or plastic tubes mimicking the difficulties faced throughout the vessels and with the devices to be implanted, allowing visualization of maneuvers due to its transparency.

They are basically useful as to have an idea of the maneuvers and especially the way of operation of the devices to utilize or to implant. They are very simple and don’t allow training or performance improvement.

Live animals have been used for ages for the learning and practice of surgical skills (3), although its use is problematic due to ethic considerations, high costs and the need of institutional facilities.5

Human cadavers are much closer to the real-world and have also been used with this purpose, nevertheless and despite being very useful for practicing dissections, sutures and so forth, also have high costs and a very limited availability. On the other hand in the endovascular field its utility is limited because of a different compliance of the tissues.5

In the area of human performance simulators many situations can be represented. They are frequently used in CPR training. Mannequins are utilized in which external cardiac massage and endotracheal intubation can be performed. Usually there is also a monitor that mimics different arrhythmias.

In the endovascular field they are utilized for practicing arterial puncture.

Figure 1 shows a simulator of this sort used for radial puncture training, built with plastic tubes connected to a pumping system that by air injection simulates the pulse wave.

The latest devices are the virtual reality (VR) simulators. We could define virtual reality7 as a computerized tridimensional interactive simulation in which the user feels immerse in an artificial ambience and perceives it as a real one because of sensorial stimuli.

Such systems are described as immersive, semi-immersive and non-immersive, according to the position of the user in relation to the stimulation.

In the immersive systems many devices are placed in the user’s head, eyes, hands, etc. (Figure 2) that will stimulate different sensorial organs giving the sensation of being inside a new ambience; this is what we’ve seen in many sci-fi movies that evidently are no longer that.

The simulators used in endovascular procedures are built on a mannequin to which is added an inlet device that mimics femoral and/or radial puncture (as the above described), through which the catheters will be inserted.

The system8 is equipped with a built-in haptic unit, a computer, 2 or 3 monitors and controls of table movements, fluoroscopy, dye injection, balloon inflation, stent deployment, etc. (Figure 3) depending on which procedures they were designed for.

Haptic strictly speaking means anything and everything related with contact, especially when it is actively used.

This word is not included in the Royal Spanish Academy dictionary and it comes from the Greek háptō (to touch, relative to tact). Nevertheless many theorists such as Herbert Read have expanded the meaning of the word “haptic” so that by default they allude with it to all non-visual and non-audible sensations that an individual experiments.

Haptic devices provide strength feedback to those interacting with virtual or remote environments. Such devices transfer sensation of presence to the operator.

They are currently available for angiography (neck and cerebral vessels, arms, legs, coronary and splanchnic arteries, aorta), angioplasties of several territories, embolization procedures, percutaneous valve implant, etc.

 

Flight Simulators

 

It’s widely acknowledged the importance of flight simulators for pilots in training. In the beginning of aviation, flying skills were transmitted from one pilot to the other.10 During World War I the U.S. built a great amount of two-seat training- planes but they spent a lot of time and money so that became impractical.

It was Edwin Albert Link (1904-1981) who developed in 1929 the first flight simulator that was marketed under the name of “Blue Box” o “Link Trainer”.

He had gotten his license as a pilot in 1927 after many years of training. Gathering the experience acquired as a pilot and working jointly with his father in an organ and piano factory, he developed the first flight simulator.

The device applied the technology used in the construction of automatic musical instruments that consists of bellows that inflate and deflate different parts, thus resembling the different movements in a plane.

In 1930 he organized a flying school named “Link Flying School” in Binghamton (New York). In 1933 he added the instruments available at that time in planes, achieving a much more sophisticated set.

However the simulator didn’t raise much interest until 1934, when the U.S. Air Force took in charge the air mail service responding to a fraud occurred in the private companies that delivered it.

A high number of accidents with casualties and losses of planes had occurred, probably due to the high demand and the difficulties faced at that time with nocturnal flights or bad weather. The Air Force then became interested in the flight simulator (“Link Trainer”), ordering the construction of 6 units as to improve pilot’s abilities.

The great booming though occurred during World War II when 10,000 “Blue Box Training” were used to improve the safety and to shorten the period of training of 500,000 pilots.

Simulators were initially used as a training step and progressively gave the chance to expert pilots to improve their skills. Simulators are today an integral part in pilot’s training being also utilized in other fields including astronauts training.

 

VR simulators in Medicine

 

In 1991 Satava11-13 proposed the use of simulators as a valuable teaching tool for the training of surgeons. However the development was initially slow probably due to skepticism of the medical community and to the lack of solid scientific evidence demonstrating their utility.

In 2002, in the Department of Surgery of the Yale University School of Medicine, it was performed the first study14 that demonstrated the transference to the operating room of the technical formation acquired by means of VR devices.

Sixteen surgical residents PGY 1 to 4 (11 men and 5 women) were randomly assigned to VR training plus a standard educational program appropriate to the year of residence or to a control group that only received standard formation. Participants were stratified by their year of residence. The surgeries were supervised by experienced surgeons blinded to the resident’s training status and recorded for a later analysis.

In this study it was observed that:

 

1. Gallbladder dissection was 29 % faster for VR-trained residents.

2. Non-VR-trained residents were 9 times more likely to transiently fail to make progress (p < 0.007) and 5 times more likely to injure the gallbladder or burn non-target tissue (p < 0.04).

3. Mean errors were 6 times less likely to occur in the VR-trained group (1.19 vs. 7.38 errors per case; p < 0.008).

 

It was concluded thus that the use of VR surgical simulation significantly improved the operating room performance of residents during laparoscopic cholecystectomy, establishing the background for more sophisticated uses of this method in assessment, training, error reduction and certification of surgeons.

These concepts were later validated by another study conducted by Grantcharov TP et al.15 who observed that while performing a laparoscopic cholecystectomy, those previously VR-trained:

1. Completed the procedure significantly faster than the control group (p=0.021).

2. With less errors (p=0.003).

3. With less movements (p=0.003) according with pre-specified scores.

 

In this way were established the basis for the utilization of this technology in skills’ teaching.

 

VR simulators in endovascular procedures

In 2004 the U. S. Food and Drug Administration accepted16 VR simulation as a useful tool during the period of training for the performance of carotid angioplasties and compromised manufacturers of carotid angioplasty systems to train proctors so as to teach physicians and students using a progressive level approach.

That very year this initiative was also backed up by the Society for Cardiovascular Angiography and Interventions, the Society for Vascular Medicine and Biology and the Society for Vascular Surgery, that jointly represent most of U. S. interventionalists performing carotid angioplasties.

On the other hand, in Europe was created the European Virtual Reality Endovascular Team (EVEREST)17 in which something similar happened, with the participation of Vascular Surgeons, Radiologists and Interventional Cardiologists.

The idea of utilizing this technology in the accreditation and/or recertification of certain skills is rapidly growing.

In a study18 of performance on a carotid stenting simulator that compared a group of experts with a group of novices, it was observed that both groups enhanced their performances but that the novices were the most benefited.

Another study19 demonstrated that simulation permits a structured evaluation of abilities in the endovascular field and correlates well with prior experience. Thereby it was concluded that simulators might prove useful in determining procedural competency and credentialing standards for endovascular surgeons.

In a recent publication20 it was established that for the recertification in Interventional Cardiology in the U. S., even though the successful completion of a simulation session (3 h of VR training plus self-testing) is not yet a mandatory step, it provides 20 out of 100 credits required.

A key role would be to count on it for the previous rehearsal of a particular case.

With all the information provided by magnetic resonance and/or computerized tomography21-23 incorporated into the simulator in DICOM (Digital Imaging and Communications in Medicine) format, it can be recreated the vascular anatomy of a given patient and can be rehearsed the appropriate maneuvers to handle it.

Lastly, several companies that market products (catheters, wires, stents, valves, etc) also recur to simulators as to show them efficiently.

VR simulators in our community

The argentine subsidiary of Cordis Corporation has introduced a VR simulator manufactured by Mentice Medical Simulators.

It’s housed in the Argentine College of Interventional Cardioangiology (ACIC) headquarters (2,146 Viamonte St. – 6th floor – Buenos Aires City).

This virtual lab includes a monitor that simulates so truly the environment of a cath lab that it appears as a real procedure. Last generation mannequins jointly with informatic and electronic devices make the trainees feel during the procedure all the sensations that they would perceive in a real case.

The procedure is followed in the first monitor where a “map” of the anatomy is displayed by X-ray simulation.

In the second monitor instead, another very realistic fluoroscopic image is displayed, that serves as a guide during the intervention. When the session ends, a report appears in the monitor with an evaluation of the user’s abilities. This report assigns a score to the procedure based upon the time consumed for performing the intervention and its level of complexity.

We have also counted intermittently with a similar simulator by Terumo that allows accomplishment of diagnostic and therapeutic coronary procedures by radial access.

It should be mentioned at last that some companies have temporarily moved their simulators for its utilization during training courses or demonstrations in courses and/or congresses, with software for percutaneous aortic valve implant, embolizations, percutaneous aortic endoprosthesis implant, etc.

 

Discussion

 

In the process of acquisition of psychomotor abilities to perform complex manual tasks like those involved in the accomplishment of endovascular interventions, after its comprehension is mandatory its integration and automation thus acquiring a relevant role the VR simulators.

Simulation (typically used in pilots training) is a way of getting experience in situations that otherwise could be dangerous for oneself or the others.

In this manner and aiming to be more realistic, many of the complications that might happen in real life, can be reproduced in virtual labs. Numerous are the benefits of this methodology that allows professional training in unusual or complex situations, enhancing diagnostic and therapeutic efficiency.

With this novel system the interventionist refines his/her technique rehearsing complex procedures several times yet without the potential risk of managing a real patient. Many interventions with a great variety of clinical situations can be practiced handling real instruments such as guide wires, catheters, balloons, stents, embolic protection devices, etc.

The system has been evolving steadily in the last years having been incorporated both in basic training in the early stages of medical residencies and as a mean of improvement for the experts by simulation of specific cases with the objective of optimizing complex procedures and ultimately in the certification and recertification of specialists.

It’s an expensive technology: a basic equipment costs up to U$S 100.000. Besides, as in every informatic system, it’s necessary its regular upgrade thus increasing even more the cost of maintenance.

Nonetheless by permitting learning, perfectioning, maintenance of abilities, accreditation and recertification it’s a system that has come to stay.

I believe we should do everything possible as to incorporate this technology in the formation of our physicians.

 

Conclusions

 

It’s estimated that about half of the adverse events occurred in the medical practice are due to medical errors that could have been prevented.

In procedures requiring practical training one of the foreseeable causes of these errors are tactics or techniques incorrectly employed.

Even though the possibility exists of performing training with animals or cadavers, this strategy might have ethical considerations or serious difficulties for reproducing all possible situations.

In the last 15 years we have witnessed an impressive development in the field of informatics, ceaseless expanding throughout all human areas and tasks.

The incorporation of VR simulation in Medicine is today a quickly evolving reality, having been incorporated both in basic training and as a mean of improvement for the experts, simulating specific cases with the objective of optimizing complex procedures and ultimately in the certification and recertification of specialists.

No doubt this is a technology that has come to stay.

1. Kohn LT, Corrigan JM, Donaldson MS, Editors; Committee on Quality of Health Care in America, Institute of Medicine. To Err Is Human: Building a Safer Health System. National Academy Press, Washington, D.C., 1999.

2. El Pequeño Larousse Ilustrado, Buenos Aires, Ediciones Larousse, 1996.

3. González Hermoso F. Errores médicos o desviaciones en la práctica asistencial diaria. Cir Esp 2001;69(6):591-603.

4. Galli A, Castro C. Programa de Formación de Formadores en Ciencias de la Salud. Volumen I. Módulo 1: Los Procesos de Enseñar y Aprender. Asociación de Amigos de la Facultad de Medicina, Buenos Aires, La Prensa Médica Argentina, 1999.

5. Reznick RK, MacRae H. Teaching surgical skills-changes in the wind. N Engl J Med 2006;355:2664-9.

6. http://www.kyotokagaku.com/products/detail01/m99.html)

7. Beutel J, Kim Y, Horii SC. Medical Imaging. Volume 3. Display and PACS. 2000. The Society of Photo-Optical Instrumentation Engineers. Chapter 2. Virtual Reality and Clinical Applications. pp. 67-102. http://books.google.com.ar/books?id=HQ2qiJd6FgEC&lpg=PA69&ots=eHKM8fpCjE&dq=medical%20virtual%20reality%20definition&pg=PA69#v=onepage&q=medical%20virtual%20reality%20definition&f=false

8. Duncan JR, Glaiberman CB. Analysis of Simulated Angiographic Procedures: Part 1.Capture and Presentation of Audio and Video Recordings. J Vasc Interv Radiol 2006;17:1979–1989.

9. http://medphyssrv1.medma.uni-heidelberg.de/

10. Roberson Museum and Science Center, Binghamton, New York. “The Link Flight Trainer. A Historic Mechanical Engineering Landmark”. June 10, 2000. http://files.asme.org/ASMEORG/Communities/History/Landmarks/5585.pdf

11. Satava RM. Virtual reality surgical simulator. The first steps. Surg Endosc 1993; 7(3)203-5.

12. Gallagher AG, Ritter EM, Champion H, Higgins G, Fried MP, Moses G, Smith CD and Satava RM. Virtual Reality Simulation for the OR. Proficiency-Based Training as a Paradigm Shift in Surgical Skills Training. Ann Surg 2005; 241: 364-372.

13. Gallagher AG, Cates Ch U. Virtual reality training for the operating room and cardiac catheterization laboratory. Lancet 2004;364:1538-40.

14. Seymour NE, Gallagher AG, Roman SA, O’Brien MK, Bansal VK, Andersen DK, Satava RM. Virtual Reality Training Improves Operating Room Performance. Results of a Randomized, Double-Blinded Study. Ann Surg 2002; 236 (4):458-464.

15. Grantcharov TP, Kristiansen VB, Bendix J, Bardram L, Rosenberg J, Funch-Jensen P. Randomized clinical trial of virtual reality simulation for laparoscopic skills training. Br J Surg 2004;91(2):146-150.

16. Gallagher AG, Cates Ch U. Approval of Virtual Reality Training for Carotid Stenting. What This Means for Procedural-Based Medicine. JAMA 2004;292(24):3024-3026.

17. Van Herzeele I, Aggarwal R. Virtual Reality Simulation in the Endovascular Field. US Cardiology 2008;5(1):41-5.

18. Hsu JH, Younan D, Pandalai S, Gillespie BT, Jain RA, Schippert DW, Narins CR, Khanna A, Surowiec SM, Davies MG, Shortell CK, Rhodes JM, Waldman DL, Green RM, Illig KA. Use of computer simulation for determining endovascular skill levels in a carotid stenting model. J Vasc Surg 2004;40:1118-25.

19. Tedesco MM, Pak JJ, Harris Jr EJ, Krummel TM, Dalman RL, Lee JT. Simulation-based endovascular skills assessment. The future of credentialing? J Vasc Surg 2008;(47)1008-14.

20. Dangas GD, Popma JJ. Recertification in Interventional Cardiology. J Am Coll Cardiol Intv 2008;(1) 332-334.

21. Cates Ch U, Patel AD, Nicholson WJ. Use of virtual reality simulation for mission rehearsal for carotid stenting. JAMA 2007;297(3):265-266.

22. Gray W, Weisz G. Patient-specific anatomy in interventional vascular simulation. Ev Today 2005 (October);67-68. http://www.endovasculartoday.com/

23. Marco J, Holmes Jr DR. Simulation: Present and Future Roles. J Am Coll Cardiol Intv 2008; (1) 590-592.

    Translated by: Alejandro A. Fernández, on behalf of the Argentine Journal of Interventional Cardioangiology.

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Virtual reality simulators in endovascular interventions

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